Earthquake Hazards and Safety

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Vocabulary

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Liquefaction: The process when an earthquake turns loose soil into liquid mud.
Aftershock: The second earthquake that comes after the first earthquake in the same place.
Tsunami: A giant wave from an ocean that is caused by an earthquake underwater.
Base-isolated Building: A building that is mounted on bearings to absorb the energy of an earthquake.

Outline

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How Earthquakes Cause Damage

• When a major earthquake strikes, it can cause lots of damage.
  • S waves can cause severe damage near the epicenter.
    • In coastal regions, giant waves pushed up by earthquakes can cause more damage.
• Local Soil Conditions
  • When seismic waves move from dense and hard rock, to loosely packed soil, the transmit the energy to the soil.
    • The soil shakes more violently than the surrounding rock.
      • The thicker the soil, the more violent the shaking will be.
• Liquefaction
  • Liquefaction occurs when the shaking of an earthquake turns soft soil into liquid mud.
    • Liquefaction is likely to occur where the soil is full of moisture.
    • Liquefaction can also trigger landslides.
• Tsunamis
  • When an earthquake jolts the ocean floor, plate movement causes the ocean floor to rise slightly to push water out of its way.
    • If the earthquake is strong enough, the water that is displaced, the water forms a large waves that are called "tsunamis"
    • The tsunami grows into a mountain of water.

Making Buildings Safer

• Most of the deaths and injuries caused by earthquakes result from damage to buildings or other kinds of structures.
  • To reduce the damage of the earthquakes, new buildings need to be made stronger and more flexible.
  • Older buildings need to be modified to be stronger and more stable.
• Choice Of Location
  • The location of a building affects the type of damage it may suffer during a big earthquake.
    • If your house is built on steep slopes, your house would have a chance of having dangerous landslides during an earthquake.
    • People should avoid building structures near earthquake faults.
      • The farther a structure is from a fault, the less strong the shaking will be during an earthquake.
• Construction Methods
  • The way in which a building or structure is constructed determines whether it can withstand an earthquake.
    • A fixed-base building is not shock-absorbing during an earthquake is happening.
    • A base-isolated building on the other hand will be shock-absorbing during an earthquake's shaking. That means that during an earthquake, it won't shake as much during an earthquake.

Protecting Yourself During an Earthquake

• The main danger for yourself during an earthquake is from falling objects and flying glass and many more objects.
  • The best way to protect yourself is to drop cover and hold beneath a table with sturdy legs.
  • If you are outdoors, go to an open area that has no electrical objects, or trees that might fall.

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